A housing extends in an axial direction of a rack shaft connected to a pinion shaft so as to cover at least the rack shaft, and has an end portion on which a cover member is fitted to cover the end portion. The housing includes a holding portion that has an inner side sinking in a radial direction of the housing, and holds the cover member, and a plurality of convex portions that protrude in the radial direction of the housing, and are circumferentially disposed on a downstream side of the holding portion in a fit-in direction of the cover member, while separating from the holding portion by a predetermined distance in the fit-in direction.
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1. A steering apparatus comprising:
a pinion shaft that has a pinion, and rotates in response to steering of a steering portion;
a rack shaft that has a rack meshing with the pinion of the pinion shaft, and moves a steered portion;
a housing that extends in an axial direction of the rack shaft, and accommodates at least the rack shaft; and
a cover member that has a connection portion connected to an end portion of the housing, and is fitted on and covers the end portion,
wherein the housing includes
a holding portion that is recessed inwardly in a radial direction of the housing, and holds the connection portion of the cover member; and
a movement restraint portion that is provided on a downstream side of the holding portion in the axial direction of the cover member, while being separated from the holding portion by a predetermined distance in the axial direction, and prevents the cover member from moving inwardly in the axial direction, wherein
the connection portion contains a first connection portion that has a flat inner surface which abuts the holding portion and
the movement restraint portion is configured to receive a downstream end of the flat inner face when the cover member is pushed inwardly in the axial direction.
2. The steering apparatus according to
wherein the predetermined distance is a distance between an upstream end of the movement restraint portion and a downstream-side end portion of the holding portion in the axial direction, and
the predetermined distance is shorter than a length of the connection portion of the cover member in the axial direction.
3. The steering apparatus according to
wherein the cover member has a specific protruding portion that protrudes from an end portion of the connection portion in the axial direction,
the movement restraint portion protrudes in a radial direction of the housing, and
a height of the downstream-side end portion of the holding portion in the axial direction is shorter than a distance between a radially inner circumference of the connection portion of the cover member and the specific protruding portion.
4. The steering apparatus according to
wherein the cover member has a specific protruding portion that protrudes from an end portion of the connection portion in the axial direction,
the movement restraint portion protrudes in a radial direction of the housing, and
a height of the downstream-side end portion of the holding portion in the axial direction is shorter than a distance between a radially inner circumference of the connection portion of the cover member and the specific protruding portion.
5. The steering apparatus according to
wherein the predetermined distance is longer than a length by which the specific protruding portion protrudes from the connection portion.
6. The steering apparatus according to
wherein the movement restraint portion includes a plurality of the protruding portions that protrude in the radial direction of the housing.
7. The steering apparatus according to
wherein the movement restraint portion protrudes in the radial direction of the housing, and is formed in a circumference direction of the housing.
8. The steering apparatus according to
wherein the connection portion includes a specific protruding portion that protrudes in the axial direction from a radially-inner side of the end portion of the connection portion.
9. The steering apparatus according to
wherein one end of the holding portion is defined by a shoulder portion and
the movement restraint portion is separated and spaced axially from the shoulder portion by the predetermined distance such that the shoulder portion is formed exclusive of the movement restraint portion.
10. The steering apparatus according to
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This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2014-054753 filed on Mar. 18, 2014, the entire content of which is incorporated herein by reference.
1. Technical Field
The present invention relates to a steering apparatus and a housing.
2. Related Art
A steering apparatus for a vehicle or the like is provided with an input portion that receives a steering force from a steering portion such as a steering wheel, and an output portion that receives the steering force from the input portion, and transmits the steering force to a steered portion such as a wheel. The steering apparatus uses a rack and pinion mechanism that has a pinion shaft and a rack shaft having a rack connected to a pinion of the pinion shaft so as to transmit a force from the input portion to the output portion.
The pinion shaft or the rack shaft is accommodated in a predetermined housing. A cover member, a so-called boot, is attached to at least the housing accommodating the rack shaft, and covers an end portion of the housing (for example, refer to JP-A-2008-230517).
The cover member is attached to the end portion of the housing at a predetermined position. Accordingly, for example, when the cover member is pushed excessively from a predetermined installation position, while being attached to the housing, it is necessary to pull the cover member back to the predetermined installation position. In the related art, there is the possibility that when the cover member is attached to the housing, it takes considerable time to align the cover member with a predetermined installation position, and working efficiencies deteriorate.
An object of the present invention is to improve working efficiencies when a cover member is attached to a housing.
An aspect of the present invention provides a steering apparatus that includes a pinion shaft that has a pinion, and rotates in response to steering of a steering portion; a rack shaft that has a rack meshing with the pinion of the pinion shaft, and moves a steered portion; a housing that extends in an axial direction of the rack shaft, and accommodates at least the rack shaft; and a cover member that has a connection portion connected to an end portion of the housing, and is fitted on and covers the end portion. The housing includes a holding portion that has an inner side sinking in a radial direction of the housing, and holds the connection portion of the cover member; and a movement restraint portion that is provided on a downstream side of the holding portion in a fit-in direction of the cover member, while separating from the holding portion by a predetermined distance in the fit-in direction, and prevents the cover member from moving inwardly in the axial direction.
Here, a distance between the movement restraint portion and a downstream-side end portion of the holding portion in the fit-in direction may be shorter than a length of the connection portion of the cover member in the fit-in direction.
The cover member may have a specific protruding portion that protrudes from an end portion of the connection portion in the fit-in direction. The movement restraint portion may protrude in a radial direction of the housing. A height of the downstream-side end portion of the holding portion in the fit-in direction may be shorter than a distance between a radially inner circumference of the connection portion of the cover member and the specific protruding portion.
A distance between the movement restraint portion and the downstream-side end portion of the holding portion in the fit-in direction may be longer than a length by which the specific protruding portion protrudes from the connection portion.
The movement restraint portion may include a plurality of the protruding portions that protrude in the radial direction of the housing.
The movement restraint portion may protrude in the radial direction of the housing, and may be formed in a circumference direction of the housing.
Another aspect of the present invention provides a housing that extends in an axial direction of a rack shaft connected to a pinion shaft so as to cover at least the rack shaft, and has an end portion on which a cover member is fitted to cover the end portion. The housing includes a holding portion that has an inner side sinking in a radial direction of the housing, and holds the cover member; and a plurality of convex portions that protrude in the radial direction of the housing, and are circumferentially disposed on a downstream-side of the holding portion in a fit-in direction of the cover member, while separating from the holding portion by a predetermined distance in the fit-in direction.
According to the aspects of the present invention, it is possible to improve working efficiencies when the cover member is attached to the housing.
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
The steering apparatus 1 of the embodiment is a steering apparatus that arbitrarily changes a travelling direction of a vehicle, and the embodiment illustrates an example in which the steering apparatus 1 is applied to a motor vehicle. The steering apparatus 1 of the embodiment is a so-called pinion-assist type.
In the embodiment, a longitudinal direction of the steering apparatus 1 illustrated in
Entire Configuration of Steering Apparatus
As illustrated in
In addition, the steering apparatus 1 includes a tie rod 23A (23B) that is provided in an end portion of the rack shaft 21, and is connected to the tire via a knuckle arm (not illustrated); a housing 30 that accommodates various members; an electric motor 40 that exerts a steering assisting force on the pinion shaft 22; and a cover member 50 that is an example of a cover member, and covers a range of from an end portion of the housing 30 to an end portion of the rack shaft 21.
In the steering apparatus 1 having the above-mentioned configuration, a steering torque exerted on the steering wheel is expressed as a relative rotation angle between the input shaft 10 and the pinion shaft 22, and a torque detecting device detects the steering torque based on the relative rotation angle between the input shaft 10 and the pinion shaft 22. An electronic control unit calculates the steering torque based on an output value from the torque detecting device, and controls the drive of the electric motor 40 based on the calculated steering torque. Torque generated by the electric motor 40 is transmitted to a worm gear (not illustrated) coaxial with a motor shaft, a worm wheel (not illustrated) meshing with the worm gear, and then is transmitted to the pinion shaft 22 coaxial with the worm wheel.
Accordingly, the torque generated by the electric motor 40 applies an assisting force with which a driver is assisted in steering the steering wheel. That is, the pinion shaft 22 rotates due to the steering torque generated by the rotation of the steering wheel and the assisting torque exerted by the electric motor 40. The rotation of the pinion shaft 22 causes the rack shaft 21 to move in the axial direction, thereby turning the wheels.
Configuration of Housing 30
The housing 30 includes a pinion housing 31P that mainly accommodates the pinion shaft 22, and a rack housing 31R that mainly accommodates the rack shaft 21.
The pinion housing 31P has a substantially cylindrical outline. The pinion housing 31P is provided in a cylindrical axial direction that intersects the axial direction of the rack housing 31R. The pinion housing 31P rotatably holds the pinion shaft 22.
The rack housing 31R has a substantially cylindrical outline, and is provided along the rack shaft 21 in the axial direction. The rack housing 31R supports the rack shaft 21 via a bush which is not illustrated, and holds, yet allows the rack shaft 21 to be movable in the axial direction. The rack housing 31R has an axial length shorter than that of the rack shaft 21. Accordingly, when the rack shaft 21 is attached to the rack housing 31R, the rack shaft 21 protrudes from an end portion of the rack housing 31R.
As illustrated in
In the embodiment, the cover holding portion 60 and the stopper portion 70 are formed integrally with a main body of the rack housing 31R. Specifically, each of the cover holding portion 60 and the stopper portion 70 is not fixed to the main body of the rack housing 31R as a separate component, but is formed as a portion of the rack housing 31R by diecasting or the like.
Configuration of Cover Member 50
As illustrated in
It is possible to use the following materials as a material of the cover member 50: a thermoplastic elastomer such as a highly cross-linked olefinic thermoplastic elastomer; chloroprene rubber; EPDM; chlorosulfonated polyethylene; and the like.
The cover member 50 covers the end portion of the rack housing 31R, a portion of the tie rod 23A (23B), and the end portion of the rack shaft 21 so, thereby preventing dust and the like from entering the rack housing 31R.
As illustrated in
The compressible and expandable portion 52 has a bellows shape. The compressible and expandable portion 52 compresses and expands in the axial direction, following a motion of the tie rod 23A (23B) in association with the movement of the rack shaft 21.
As illustrated in
An inner circumference of the housing connection portion 53 protrudes inwardly in the radial direction, and thus can be connected to the cover holding portion 60 which will be described later. An outer circumference of the housing connection portion 53 sinks inwardly in the radial direction, and thus a substantially annular second fixing member 82 (refer to
The molded protruding portion 54 protrudes from the end portion of the housing connection portion 53 in the axial direction. In the embodiment, for example, the molded protruding portion 54 can be molding processed when the cover member 50 is molded. For example, the housing connection portion 53 is disposed in an end portion of the cover member 50. When the housing connection portion 53 is molded into a predetermined shape, an extra space is formed further outside of a molding flask in such a manner that the molding flask for the molding of the housing connection portion 53 is sufficiently filled with a material. Accordingly, in the embodiment, the material flows into the extra space, and thus the molded protruding portion 54 is formed in the end portion of the housing connection portion 53.
Subsequently, the length of each of the configuration portions of the cover member 50 described above will be described with reference to
The first connection portion 531 has an axial length “L1”. The first connection portion 531 has a radial thickness “T1”. The molded protruding portion 54 has a protrusion length “B1” by which the molded protruding portion 54 protrudes from the housing connection portion 53 (the third connection portion 533) in the axial direction. The molded protruding portion 54 has a height “H1” that is a radial height from an inner circumference of the first connection portion 531.
Here, first, the structure of a housing of each of comparative examples will be described so that the cover holding portion 60 of the embodiment can be described.
As illustrated in
For this reason, the molded protruding portion 54 of the cover member 50 is brought into contact with the stopper 912. As a result, there is a problem in that the housing connection portion 53 cannot be accommodated in the holding groove 911, and the cover member 50 is unreliably attached to the housing 910.
In addition, as illustrated in
For this reason, the molded protruding portion 54 positioned at the end portion of the housing connection portion 53 is brought into contact with the end portion 922. As a result, there is a problem in that the housing connection portion 53 is not accommodated in the holding groove 921, and the cover member 50 is unreliably attached to the housing 920.
In addition, as illustrated in
Accordingly, there is a problem in that a gap W is formed between the holding groove 931 and the end portion of the housing connection portion 53, the cover member 50 can move in the axial direction by the amount of gap W, and the cover member 50 is unreliably attached to the housing 930.
Configuration of Cover Holding Portion 60
As illustrated in
The cover holding portion 60 has a bottom portion 611 that is formed in the axial direction; a first wall portion 612 that rises in the radial direction from one side in the axial direction of the bottom portion 611; and a second wall portion 613 that rises in the radial direction from the other side in the axial direction of the bottom portion 611. As illustrated in
The bottom portion 611 faces the first connection portion 531 of the housing connection portion 53. In the embodiment, as illustrated in
The first wall portion 612 is a surface facing the other side in the axial direction. The first wall portion 612 faces the second connection portion 532, thereby preventing the housing connection portion 53 from moving to one side. The height of the first wall portion 612 is set so as to prevent the housing connection portion 53 from slipping out of its position when the attached housing connection portion 53 is pulled to one side.
The second wall portion 613 is a surface facing one side in the axial direction. The second wall portion 613 faces the third connection portion 533, thereby preventing the housing connection portion 53 from moving to the other side.
The height H2 (a distance from the bottom portion 611 to the end portion 613E in the circumferential direction) of the second wall portion 613 is set so as to prevent the housing connection portion 53 from slipping out of its position when the attached housing connection portion 53 is pushed to the other side, that is, inwardly in the axial direction. In the embodiment, the second wall portion 613 has the height H2 less than the height H1 (refer to
Configuration of Stopper Portion 70
As illustrated in
In the embodiment, the plurality of protruding portions 71 is provided. Accordingly, when the cover member 50 is attached to the rack housing 31R, the rack housing 31R can receive the cover member 50 substantially straight in the axial direction. As a result, when the cover member 50 is attached to the rack housing 31R, the cover member 50 does not incline, and it is possible to improve working efficiencies. In addition, since the plurality of protruding portions 71 is disposed at the substantially equal intervals in the circumferential direction, the rack housing 31R can better receive the cover member 50 without an inclination.
As illustrated in
The distance B2 is preferably constant, thereby it is possible to correspond to a plurality of types of cover members 50 having different shapes. In the embodiment, the stopper portion 70 is formed corresponding to the molded protruding portion 54 of the cover member 50 illustrated in
A protruding height P2 is a height by which the protruding portion 71 protrudes from the rack housing 31R, and is set in such a manner that the protruding portions 71 can receive the cover member 50 when the cover member 50 is pushed, and prevent the cover member 50 from moving inwardly beyond the protruding portions 71 in the fit-in direction. In the embodiment, the protruding height P2 is set to be greater than or equal to at least the thickness T1 of the first connection portion 531 of the housing connection portion 53. In addition, the protruding height P2 is preferably set in such a manner that the cover member 50 can be prevented from moving to the other side. From the viewpoint that it is necessary to suppress an increase in weight of the rack housing 31R, the protruding height P2 is preferably set in such a manner that the protrusion of the protruding portion 71 does not exceed the maximum outer diameter of the cover member 50 and is smaller than or equal to the outer diameter of the cover member 50.
In the embodiment, the stopper portion 70 includes the plurality of protruding portions 71 formed discretely in the circumferential direction, but the present invention is not limited to the embodiment.
As illustrated in
As illustrated in
As illustrated in the embodiment, when the stopper portion 70 is molded integrally with the rack housing 31R by diecasting or the like, the stopper portion 70 preferably includes the plurality of protruding portions 71 from the viewpoint of manufacturing efficiencies of the rack housing 31R. That is, typically, when being die-cast manufactured, the rack housing 31R is formed by using a plurality of the molding flasks, and the molding flasks are removed in the radial direction of the rack housing 31R. In this manner, the stopper portion 70 is not continuously formed in the circumferential direction, but is formed in a state of being divided into the plurality of protruding portions 71, and thus it is possible to reduce a step of eliminating so-called burrs that may be formed in the stopper portion 70.
For example, as illustrated in
In addition, the height H2 of the second wall portion 613 of the cover holding portion 60 is set to be less than the height H1 of the molded protruding portion 54. For this reason, the molded protruding portion 54 provided in the end portion of the cover member 50 is not brought into contact with the stopper portion 70. In addition, the cover holding portion 60 can hold the housing connection portion 53 in a state of not deviating in the axial direction and the radial direction.
In the embodiment, when the cover member 50 is attached to the rack housing 31R in this manner, it is possible to improve working efficiencies.
In the embodiment, as described above, the distance B2 between the stopper portion 70 and the cover holding portion 60 is set to be shorter than the length L1 of the housing connection portion 53. For this reason, when the housing connection portion 53 is pushed inwardly in the axial direction, passing the cover holding portion 60, it is possible to reduce a force required to pull the housing connection portion 53 back to the cover holding portion 60.
That is, the housing connection portion 53 has an inner diameter smaller than that of other portions of the cover member 50. The cover member 50 is made of a relatively hard material for its functions. When the housing connection portion 53 is fitted in its entire length on the outer circumference of the rack housing 31R having an outer diameter greater than that of the cover holding portion 60, an operator requires a relatively strong force to pull the cover member 50 out. There is a high possibility that when a force of pulling the cover member 50 is strong, and the cover member 50 is excessively pulled back, the housing connection portion 53 deviates to one side of the cover holding portion 60. At this time, it is necessary to again adjust the attachment position of the cover member 50.
In contrast, in the embodiment, as described above, since a distance between the stopper portion 70 and the cover holding portion 60 is set to the distance B2, at least a portion of the housing connection portion 53 stays in the cover holding portion 60 even when the cover member 50 is pushed. Accordingly, it is possible to make a force required to pull the cover member 50 back relatively small. In the embodiment, it is possible to improve working efficiencies when the cover member 50 is attached to the rack housing 31R.
In the embodiment, the electric power steering apparatus is described as an example, but particularly, the present invention is not limited to the embodiment. The present invention may be applied to the electric power steering apparatuses of other types such as a rack-assist electric power steering apparatus. The present invention may be applied to a hydraulic power steering apparatus that provide an assisting force, or a manual steering apparatus that does not provide an assisting force.
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Sep 25 2014 | ZAIKE, YASUHIRO | Showa Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 033827 | /0563 | |
Sep 26 2014 | Showa Corporation | (assignment on the face of the patent) | / | |||
Jan 01 2021 | Showa Corporation | HITACHI ASTEMO, LTD | MERGER SEE DOCUMENT FOR DETAILS | 059682 | /0321 |
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